Package trace

func ContextWithTrace ¶

func ContextWithTrace(ctx context.Context, trace *Trace) context.Context

ContextWithTrace returns a context with trace included in the context values, keyed by ContextTraceKey.

type ContextTraceKey ¶

ContextTraceKey provides a common key for traces in context.Context values.

type ContextTraceKey struct{}

type Field ¶

Field is a key value pair that provides additional details about the trace.

type Field struct {
    Key   string
    Value interface{}
}

type Trace ¶

Trace keeps track of a set of "steps" and allows us to log a specific step if it took longer than its share of the total allowed time

type Trace struct {
    // contains filtered or unexported fields
}

func FromContext ¶

func FromContext(ctx context.Context) *Trace

FromContext returns the trace keyed by ContextTraceKey in the context values, if one is present, or nil If there is no trace in the Context. It is safe to call Nest() on the returned value even if it is nil because ((*Trace)nil).Nest returns a top level trace.

func New ¶

func New(name string, fields ...Field) *Trace

New creates a Trace with the specified name. The name identifies the operation to be traced. The Fields add key value pairs to provide additional details about the trace, such as operation inputs.

func (*Trace) Log ¶

func (t *Trace) Log()

Log is used to dump all the steps in the Trace. It also logs the nested trace messages using indentation. If the Trace is nested it is not immediately logged. Instead, it is logged when the trace it is nested within is logged.

func (*Trace) LogIfLong ¶

func (t *Trace) LogIfLong(threshold time.Duration)

LogIfLong only logs the trace if the duration of the trace exceeds the threshold. Only steps that took longer than their share or the given threshold are logged. If klog is at verbosity level 4 or higher and the trace took longer than the threshold, all substeps and subtraces are logged. Otherwise, only those which took longer than their own threshold. If the Trace is nested it is not immediately logged. Instead, it is logged when the trace it is nested within is logged.

func (*Trace) Nest ¶

func (t *Trace) Nest(msg string, fields ...Field) *Trace

Nest adds a nested trace with the given message and fields and returns it. As a convenience, if the receiver is nil, returns a top level trace. This allows one to call FromContext(ctx).Nest without having to check if the trace in the context is nil.

func (*Trace) Step ¶

func (t *Trace) Step(msg string, fields ...Field)

Step adds a new step with a specific message. Call this at the end of an execution step to record how long it took. The Fields add key value pairs to provide additional details about the trace step.

t := New("frobber")

time.Sleep(5 * time.Millisecond)
t.Step("reticulated splines") // took 5ms

time.Sleep(10 * time.Millisecond)
t.Step("sequenced particles") // took 10ms

klog.SetOutput(os.Stdout) // change output from stderr to stdout
t.Log()

func (*Trace) TotalTime ¶

func (t *Trace) TotalTime() time.Duration

TotalTime can be used to figure out how long it took since the Trace was created